海水环境生物腐蚀污损与防护

以海水环境生物腐蚀污损与防护为中心,就国内外与其相关的报道进行综述分析,并提出建议。首先,分析污损生物的分布与特征,得出污损生物群落的组成和结构对海域、季节、水深、工程结构类型等的依赖性,突出海水环境生物腐蚀污损的复杂性。然后,解析生物附着污损对海水环境腐蚀速率的影响,突出附着生物是导致金属材料腐蚀速率增大的重要因子。再次,介绍海水环境生物腐蚀污损防护技术的现状,分析主要防护技术的优缺点,并展示其在不同行业的联用。最后,提出对海水环境生物腐蚀污损研究工作的建议,包括建立各海域的生物腐蚀污损数据库、大力研制发展绿色生物腐蚀污损控制技术、加强对海洋生物腐蚀污损基础性研究工作的投入、尽快建立海洋生物腐蚀评价标准和规范等。     

城市污水管网中污染物冲刷与沉积规律

为探明城市污水管网中污染物的冲刷与沉积规律,对西安市污水管网进行实际调研,结果表明,污水支管和干管的沉积物厚度时变化较大,变化量分别为0~24 mm和0~12 mm,管道污水中颗粒态污染物发生沉积和冲刷的概率高;而污水主干管的沉积物厚度时变化较小,管道内颗粒物沉积与沉积物冲刷水平维持相对平衡.为进一步明确污水中污染物浓度变化与水流流速的关系,建立了污水管道冲刷与沉积模拟中试装置,研究了不同流速下管道中碳(有机)、氮、磷三类污染物含量和粒径分布的变化规律.结果表明,随着污水流速的增加,冲刷强度增大,管道中污染物浓度急剧升高,通过粒径分布监测结果可知,管道中有机污染物易存在于粒径较大的颗粒物上,氮、磷类污染物易吸附在粒径较小的颗粒物上;当流速小于0.6 m·s~(-1)时,污水中颗粒态污染物的沉积作用大于冲刷作用,发生物理沉积,造成污水中碳源不足,当流速大于0.6 m·s~(-1)时,水流冲刷强度增大,沉积物被水流大量携带,但污水中碳类有机污染物的增加比重大于氮和磷类污染物,使现有污水碳源不足得到改观,利于生物脱氮除磷工艺的碳源需求.     

气相分子吸收光谱法在海水无机氮测定中的适用性研究

为探究气相分子吸收光谱法在海水无机氮测定中的适用情况,在检出限的10～20倍、30～50倍、50～100倍3个浓度范围内开展了准确度、加标回收率和方法比对试验。结果表明,采用气相分子吸收光谱法测定海水亚硝酸盐氮(0～0.100 mg/L)、硝酸盐氮(0～0.400 mg/L)、氨氮(0～0.200 mg/L)时,标准曲线均具有很好的线性,线性拟合度均在0.999 3以上,检出限依次为0.000 8、0.004、0.004 mg/L,且该方法不具有盐效应,适用于海水样品的检测。当样品浓度太低时,气相分子吸收光谱法测定结果的准确度较低,因此,建议仅在亚硝酸盐氮浓度高于0.030 mg/L、硝酸盐氮浓度高于0.100 mg/L、氨氮浓度高于0.090 mg/L时使用该方法,对应的海域为河口及近岸等无机氮含量较高的海域。此外,为保证测定结果的准确度,每个样品需平行测定2～3次。     

Two leaks detection in viscoelastic pipeline systems by means of transient

This paper presents a technique for detecting and locating leaks in a single viscoelastic pipe, by means of transient analysis. The system studied is a reservoir-pipe-valve structure. The viscoelastic behavior of the pipe wall material is modeled by a generalized KelvinVoigt model. To determine the leak location, the mathematical formulation has been solved by the method of characteristics. The approach by the method of characteristics is often chosen because it is based on the concept of acoustic wave propagation which is the main mechanism of all transient events considered. The presence of the two leaks in a pipe partially reflects pressure waves initiated by the sudden closure of a downstream shut-off valve. These waves affect the shape and the amplitude of the time-history-pressure. The computed results describe the influence of the presence of two leaks on pressure time-history and the effect of leaks locations and sizes on the pressure signal behavior. The effect of the pipe wall viscoelasticity on the two leaks detection and sizing is also discussed. The leaks discharges are determined by resolving two independent equations derived from literatures and based on transient analysis. The friction and leaks depths effects on two leaks locations and sizing are involved.     

NaClO2海水溶液强化烟气脱硝效果的实验研究

海水中富含多种盐类,具有一定碱性,是天然的缓冲剂,在脱硫脱硝方面具有良好的应用前景.利用不同浓度的NaClO_2溶液进行废气循环喷淋脱硝实验.结果表明,NaClO_2模拟海水溶液与NaClO_2淡水溶液都能将NO完全脱除,且当NO完全被脱除时,模拟海水溶液的持续时间比淡水溶液更长,模拟海水中所含有的少量HCO_3~-和OH~-是造成这种差异的主要原因.滴定实验结果显示0.066 mmol的HCl就可使NaClO_2淡水溶液的pH值降到7,而NaClO_2模拟海水溶液的pH值降到7需要0.114 mmol的HCl;在循环喷淋脱硝过程中NaClO_2模拟海水溶液的pH值基本维持在7以上.离子色谱检测结果显示脱硝后溶液中主要阴离子为Cl~-和NO_3~-.基于质量平衡计算结果,当NaClO_2浓度为20 mmol·L~(-1)时,在脱硝过程中淡水溶液中NaClO_2的利用率为56%,而模拟海水溶液中NaClO_2的利用率可达67.25%,提高幅度为20.1%.     

序批式曝气生物滤池处理含海水污水中的硝化性能

采用序批式曝气生物滤池工艺,以牡蛎壳为填料、含海水污水为处理对象,系统考察不同的海水含率、原水葡萄糖和氨氮浓度等原水条件下的硝化性能。结果表明,对于海水含率在40%到100%的污水处理,氨氮去除率可达到95%以上,表明该生物滤池中的氨氧化菌(AOB)可耐受较高的海水盐度;耐海水盐度的驯化硝化细菌中,AOB的耐盐度抑制能力强于亚硝酸氧化菌(NOB),当海水含率大于70%时,NOB的活性更容易受到抑制。在高海水盐度下,降低原水的葡萄糖与氨氮浓度可提高NOB活性。牡蛎壳附着生物膜与液相悬浮污泥中的AOB 和NOB均参与了氨氮去除,生物膜中的AOB和NOB活性高于悬浮污泥。     

NH4NO3-Pd(NO3)2联合基体改进剂石墨炉法测海水中痕量镉

用NH4NO3-Pd(NO3)联合基体改进剂,石墨炉法直接测海水中痕量镉.通过不同条件的实验,确定了最佳的分析条件;并通过对实际样品平行性和加标回收率的测定,验证了方法的精密度和准确度.建立了空白实验,在0.19～5.0μg/L线性范围内,镉的最低检出限为0.19μg/L.实验结果表明,该方法快速方便,提高了分析效率,准确度高,精密度好.     

PEAKING STORAGE TANKS FOR WATER SUPPLY SYSTEMS1

ABSTRACT: Construction of a “peaking storage tank” may reduce the operational cost of municipal water in the availability of a time-of-use energy rate. A peaking storage tank is used for storing water that is pumped from wells or other sources of supply during off-peak periods when energy costs are less for use during periods of on-peak water demand. The optimal size of a peaking storage tank is that which results in the minimum total cost, which includes both the storage construction cost and the cost of operation of the pumps. The operational cost for a given time-of-use rate is determined by help of a pipe network simulation model solved by the Newton-Raphson technique and a dynamic programming optimization model. A more simplified method is also introduced. Analyses show that low off-peak energy costs make the construction of peaking storage tanks economically attractive and reduce on-peak energy use, which results in electrical load leveling.     

大口径高温高压管道下沉分析

以某电厂的主蒸汽管道为例,对其支吊架进行冷、热态检验,发现炉侧连续恒力吊架冷态时指针卡死下极限位置,热态时实际垂直热位移值较小,与设计严重不符。根据现场情况和应力计算结果综合分析,发现管道壁厚存在严重误差导致管道下沉。针对以上情况,首次提出了支吊架配置改造方案需要考虑的4个方面,给解决此类问题提供帮助。     

供热管道波纹管补偿器裂纹泄漏的分析及对策

通过对热电厂直埋供热管道波纹管补偿器裂纹泄漏事故的调查分析,找出了问题所在,并提出了解决应力腐蚀问题可行的对策.